The oxidation of ethylene to ethylene oxide can be accomplished by reaction with air or oxygen in the presence of a silver catalyst mounted on a suitable carrier, with the optional addition of small amounts of certain chlorinated hydrocarbons which serve to moderate the catalyst. Under normal operating conditions, the oxidation reaction produces mostly ethylene oxide, with carbon dioxide and water as side products. The reaction is exothermic.
The construction of the reactor where the oxidation is carried out can be similar to a vertical shell and tube heat exchanger. The tubes are filled with the catalyst while the shell side of the reactor is provided with a coolant. Suitable pumps, heat exchangers, separator drums, and/or condensers can be employed to condense, or separate, and recirculate the coolant.
In some cases, without careful temperature control, the oxidation reaction can proceed to the formation of carbon dioxide and water vapor. This not only reduces the yield, but is a much more exothermic reaction which can cause “hot spots” within the reactor and a consequent increase in the demands made upon the cooling system. In addition, the “hot spots” can increase local temperatures and can spread rapidly to the reactor outlet, leading to a bulk gas phase ignition, referred to herein as a “decomp”.